This application proposes the renewal of The National Center for Muscle Rehabilitation Research at the University of California, San Diego. The proposal consists of five core units that span three departmental boundaries and two schools within the University. The five cores are Muscle Histology, Muscle Biomechanics, Muscle Imaging, Muscle Metabolism and Program Administration. The program is structured to foster cooperation and synergy across cores. This organization will facilitate interaction among program faculty and minimize the overhead needed to accomplish Rehabilitation Research. In addition to research cores, the program will advertise state-of-the-art workshops regarding muscle structure, function, and imaging appropriate for the Rehabilitation professional. The PIs anticipate tremendous interest by the Rehabilitation community since functional restoration by Rehabilitation is based on a healthy muscular system - muscle comprising so much of normal body mass. Collaborative opportunities are proposed for visiting Rehabilitation professionals that will match interests with one or more of the core labs in order to leverage the technologies available at the UCSD campus on behalf of the Rehabilitation professional. Finally, a program of pilot grants for both intramural and extramural applications is proposed to encourage young faculty in the formative stage of their careers to take advantage of the state-of-the-art research facilities and beautiful living conditions in La Jolla. The Medical Rehabilitation Research Infrastructure Program in Muscle at UCSD will leverage the tremendous scientific expertise available at UCSD for the benefit of the Rehabilitation professional in the short term and for the benefit of their patients in the long-term.